SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd87756baace62352779efeaffcbb52c0bdfa595765040a928090c74181405176' 
  AND token = 'AjJKuGJ1zVXL8mggd7TsixRoPyAB7cyOkaNovhKmGdg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}